To protect miners in the event of a mining incident involving the release of toxic gas, smoke or dust, or an incident that reduces the oxygen content of the air; some mines have an underground shelter that provides the miners with a temporary place of refuge isolated from the contaminated air, or air having a low oxygen content. Such shelters often have a sealed door, emergency provisions, and means for providing at least a limited supply of breathable air. The miners can stay in the shelter until they are rescued or until it is safe to leave.